1. Field of the Invention
This invention relates to a photographic camera with information reading function into which camera control information can be input from an information input system, and more particularly to a photographic camera which reads the camera control information with a bar code sensor for reading information on film from a bar code plate on a film magazine.
2. Description of the Related Art
There has been known a film magazine in which a data disk carrying thereon bar codes representing information inherent to the film magazine such as the ISO sensitivity, the number of exposure frames and the like of the film is provided to rotate integrally with the spool. The bar codes comprise a plurality of bars of a low reflectivity and spaces of a high reflectivity which are alternately arranged in the direction of rotation of the data disk. Further a particular portion such as a black quiet zone showing a data read begin position or a data read end position is provided at the leading end and/or the trailing end of the bar codes.
Further there has been known a photographic camera in which a film magazine provided with such a data disk is loaded as disclosed, for instance, in U.S. Pat. No. 5,025,274. The camera disclosed in the United States patent is provided with a photosensor for reading the bar codes, and the bar codes are read by the photosensor while the film magazine is loaded in the camera and the first frame of the film is set to the film aperture of the camera. The camera automatically adjusts various mechanisms in the camera such as the stop on the basis of the data read by the photosensor.
Further there has been known a photographic camera in which correction of output of a light measuring system, intensity of flash, battery check level, properties of lens barrel and the like are stored in a ROM and a microcomputer in the camera performs a sequence of operation referring to the ROM. Recently in some cameras, a nonvolatile storage such as an EEPROM (Electrically Erasable & Programmable ROM) is employed in place of a ROM, which is not reloadable, so that such camera control information can be checked and corrected after assembly of the camera.
In a photographic camera wherein the EEPROM is employed, an exclusive electric terminal must be provided to connect the EEPROM to an external instrument for writing information or read information from the EEPROM. It is necessary that the electric terminal is not accessible to a common user but permits connection with an external instrument in case of necessity. Accordingly the mechanism for exposing the terminal is inherently complicated.
So we have proposed a photographic camera with information reading function in which a reflective photosensor is provided in a magazine chamber in which a film magazine having a bar code plate rotated integrally with the film spool is loaded and information on the film is read by the photosensor on the basis of reflected light from the bar code plate while camera control information is read also by the photosensor on the basis of light projected from a light projecting portion of an information input system opposed to the photosensor. See Japanese Patent Application Nos. 4(1992)-233910 and 5(1993)-150577.
When the camera control information is read by the reflective photosensor for reading the film information, the sensor-occupied space can be saved and the manufacturing cost of the camera can be lowered.
Since the reflective photosensor receives reflected light from the bar code plate which is relatively weak, the photoelectric convertor circuit of the photosensor must have a certain amplification factor.
On the other hand, when the photosensor directly receives the light from the light projecting portion of the information input system, the amplification factor of the photoelectric convertor circuit need not be so large.
Further, since the rotational speed of the bar code plate is not so high and the density of the bar codes on the bar code plate is not so high, change in the signal is relatively gentle when the information born by the bar code is to be read, and accordingly response speed of the photoelectric convertor circuit need not be so high.
On the other hand, when the information from the information input system is to be read, hundreds to thousands Bauds of response speed of the photoelectric convertor circuit is generally required.
Accordingly it is preferred that the arrangement of the circuit for photoelectric conversion of the information signal read by the reflective photosensor be changed according to the information to be read.